(a) To pay the costs of a project, the county may issue bonds payable from and secured by a pledge of the net revenue of the project. The cost of a project may include:
(1) legal, fiscal, and engineering expenses; and
(2) interest during the construction of the project.
(b) If provided in the order issuing a bond, bonds issued under Subsection (a) may be additionally secured by an ad valorem tax imposed under Section 9, Article VIII, Texas Constitution. If the county places any part of the ad valorem tax in a permanent improvement fund, only the ad valorem taxes in that fund may be used as the additional security.
(c) Before a county may issue bonds under Subsection (a) to pay for a project, the bonds must be approved in an election held under Section 1477.057. If an ad valorem tax is to be imposed under Subsection (b) to secure bonds, the tax must also be approved at the election held to approve the issuance of the bonds.